U.S. patent number 6,107,813 [Application Number 08/606,979] was granted by the patent office on 2000-08-22 for probe card changer system and method.
This patent grant is currently assigned to Xandex, Inc.. Invention is credited to Tom Richards, Roger Sinsheimer.
United States Patent |
6,107,813 |
Sinsheimer , et al. |
August 22, 2000 |
Probe card changer system and method
Abstract
A prober tester interface system and a method for loading a
probe card into a prober. The interface system includes a stiffener
for holding a probe card, the stiffener having an upper surface, a
perimeter, an underside, a plurality of recesses in the underside
around the perimeter, and first and second alignment holes. A theta
ring for holds the stiffener in the prober, the theta ring having
first alignment pins for engaging the first alignment holes, a
plurality of lock cylinders for engaging the recesses, and a
machined lip against which the upper surface of the stiffener is
forced by the lock cylinders. A loader is coupled to the prober for
loading the stiffener in and unloading the stiffener from the theta
ring, the loader having second alignment pins for engaging the
second alignment holes. A theta drive assembly is coupled to the
theta ring for rotating the theta ring to align the probe card with
the test head. In a specific embodiment, the test head includes a
contactor, and the theta ring includes a plurality of clamp
cylinders for locking the contactor in theta and Z while a probe
card is being loaded or unloaded.
Inventors: |
Sinsheimer; Roger (Petaluma,
CA), Richards; Tom (Petaluma, CA) |
Assignee: |
Xandex, Inc. (Petaluma,
CA)
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Family
ID: |
22847786 |
Appl.
No.: |
08/606,979 |
Filed: |
February 26, 1996 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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226154 |
Apr 11, 1994 |
5528158 |
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Current U.S.
Class: |
324/750.22;
324/756.03 |
Current CPC
Class: |
G01R
1/07314 (20130101) |
Current International
Class: |
G01R
1/073 (20060101); G01R 031/02 () |
Field of
Search: |
;324/754,755,757,758 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1-161173 |
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Jun 1989 |
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JP |
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0001141 |
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Jan 1990 |
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JP |
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2066590 |
|
Jul 1981 |
|
GB |
|
2242081 |
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Sep 1991 |
|
GB |
|
Other References
Sales brochure entitled "BE6000 Series Base Entry Probe Interface
System," Fresh Technology Group, undated. .
Sales brochure entitled DS1994 Touch Time and Memory, Dallas
Semiconductor, undated. .
Advertising brochure entitled "Automation and Cleanliness--Advanced
TEL Technology Leads the Way to New Levels," TEL, undated. .
Page from DS9092K User's Manual, (Aug. 1991)..
|
Primary Examiner: Karlsen; Ernest F.
Assistant Examiner: Kobert; Russell M.
Attorney, Agent or Firm: Townsend and Townsend and Crew
LLP
Parent Case Text
This is a Division of application Ser. No. 08/226,154 filed Apr.
11, 1994, now U.S. Pat. No. 5,528,158.
Claims
What is claimed is:
1. A prober to test head interface, comprising:
a stiffener for holding a probe card, the stiffener having an upper
surface, a perimeter, an underside, a plurality of recesses in the
underside around the perimeter, and first and second alignment
holes;
a theta ring for holding the stiffener, the theta ring having first
alignment pins for engaging the first alignment holes, a plurality
of lock cylinders for engaging the recesses, and a machined lip
against which the upper surface of the stiffener is forced by the
lock cylinders;
a loader coupled to the prober for loading the stiffener in and
unloading the stiffener from the theta ring, the loader having
second alignment pins for engaging the second alignment holes,
wherein the loader comprises an arm assembly coupled to the prober
for moving the stiffener in first and second directions, the first
direction being substantially parallel to a plane defined by the
upper surface of the stiffener, and the second direction being
substantially perpendicular to the plane, the arm assembly
comprising:
a Z mechanism coupled to the prober;
a first slide assembly coupled to the Z mechanism;
a first air cylinder coupled to the first slide assembly;
a second slide assembly coupled to the first air cylinder;
a second air cylinder coupled to the second slide assembly; and
a hand coupled to the second air cylinder for holding the
stiffener, the second alignment pins being located on the hand;
wherein the first air cylinder moves the second slide assembly with
respect to the first slide assembly in the first direction, the
second air cylinder moves the hand with respect to the second slide
assembly in the first direction to a position directly below the
theta ring, and the Z mechanism moves the arm assembly in the
second direction, thereby causing the first alignment holes to
engage the first alignment pins on the theta ring; and
a theta drive assembly coupled to the theta ring for rotating the
theta ring to align the probe card with the test head.
2. The prober to test head interface of claim 1 wherein the loader
further comprises a magazine frame having at least one docking
receptacle, and the interface further comprises at least one
docking pin for engaging the at least one docking receptacle.
3. The prober to test head interface of claim 1 wherein the
stiffener comprises a memory for storing operational data regarding
the probe card.
4. The prober to test head interface of claim 3 wherein the
operational data comprises a previous theta location for the probe
card, and the theta drive assembly comprises a motorized belt
drive, the motorized belt drive having a position feedback
mechanism which the motorized belt drive employs to rotate the
theta ring and position the probe card at the previous theta
location.
5. The prober to test head interface of claim 3 wherein the memory
comprises a touch memory positioned on the underside of the
stiffener.
6. The prober to test head interface of claim 5 wherein the loader
further comprises a memory reader for contacting the touch memory
and reading the operational data stored therein.
7. The prober to test head interface of claim 1 wherein the test
head comprises a contactor, and the theta ring comprises a
plurality of clamp cylinders for locking the contactor in theta
while a probe card is being loaded or unloaded.
8. The prober to test head interface of claim 7 wherein the
stiffener comprises third alignment holes for engaging pins on the
contactor.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to the field of electronic
test systems. More specifically, the invention provides an improved
method and apparatus for performing probe tests on semiconductor
wafers.
Various types of wafer test and probe equipment are well known to
those of skill in the art, and are widely used in semiconductor
manufacturing operations. Such equipment is used to provide
electrical signals to a plurality of dies, generally formed on a
semiconductor wafer, and to monitor the response of the dies to the
electrical signals. Wafer test and probe equipment is made by a
variety of manufacturers including, for example, Electroglas, Inc.,
KLA Instruments, Teradyne, Inc., Schlumberger Technologies, and
LTX--Trillium.
Semiconductor wafer testing is normally conducted prior to wafer
dicing and chip packaging. The wafer is placed on a prober chuck,
indexed, and each die is tested. The testing operation normally
involves placing a probe card with a number of probe tips in
contact with a particular die at selected locations, such as, for
example, the bond pads. Predetermined voltage patterns are then
applied to the die, and the response of the die to the signals is
monitored. If the die exhibits an appropriate response, the die is
presumed to be "good." If the monitored response falls outside
performance parameters, the die is either rejected, or appropriate
remedial action is taken. Such wafer tests are performed on a wide
variety of semiconductor products ranging from DRAMs and SRAMs to
microprocessors.
Because modem semiconductor devices are being developed to operate
at higher and higher speeds, "overhead" test techniques have been
developed to keep signal transmission lines as short as possible.
Short transmission lines reduce cross-talk between adjacent lines
and eliminate other
undesirable high frequency effects. In overhead testing techniques,
a section of the tester referred to as the test head is positioned
over the wafer under test and then docked to the prober. The
interface between the test head and the wafer comprises a printed
circuit board (Performance Interface Board or PIB), a plurality of
downwardly extending spring loaded pins (Pogo.RTM. pins) and a
probe card. The PIB and the Pogo pins are coupled to the test head
which, when docked, causes the pins to come into contact with the
probe card. The probe card is a custom printed circuit board which
forms the connection between the Pogo pins and the probes (pins)
which actually contact the wafer. Some systems use the weight of
the test head to compress the Pogo pins against the probe card.
Others employ a vacuum which forms a seal on the probe card to
supply the necessary force. Still other systems have combined the
PIB with the probe card to further reduce the signal transmission
distances from the test head to the wafer. This has resulted in an
increase in the size of stiffener/probe card assemblies.
While enjoying some measure of success, such prior systems have
also encountered certain difficulties. One such difficulty is
related to the fact that the arrangement of the bonding pad (used
for testing) locations for various devices belonging to a family of
products will differ from device type to device type, thus
requiring different probe cards for testing each device type. For
example, the arrangement of probes on a probe card for testing 1M
DRAMs is radically different from the arrangement of probes on a
probe card intended for testing of 4M DRAMs. Therefore, when the
user of a prior system desires to switch the wafer product being
tested, or if probe card gets damaged or dirty during testing, it
becomes necessary to remove and replace the currently installed
probe card. This is a time consuming and difficult task for a
number of reasons. First, in many systems the probe card is mounted
under the test head, which must be undocked before the probe card
may be removed. This proves difficult because most test heads weigh
between 250 and 750 pounds. Additionally, in most systems, the
interface between the test head and the probe card must be
disassembled and then reassembled. Finally, recalibration of probe
card and test head positioning is required after replacement of a
probe card.
As device density increases due to advances in semiconductor
fabrication, probe card probes density also increases. Thus, the
performance of the probe card interface system has become
increasingly critical to successful device testing. In order to
ensure proper contact between probe card probe tips and the device
under test, significantly tight alignment must be maintained among
the probes. In addition, at high densities, the probe card is
commonly subjected to significant force while probes are in contact
for testing. Because of the often delicate nature of probe card
pins, such pressure frequently causes pin damage and/or
misalignment. Thus, probe cards often require maintenance after
repeated contacts with semiconductor wafers.
Conventionally, those of skill in the art have had no effective way
of recording the operating history of a probe card. Therefore,
contact failures only have been detected after the fact using, for
example, a method such as the one disclosed by U.S. Pat. No.
5,019,771, the entire specification and drawings of which are
herein incorporated by reference. Using such reactive methods,
however, a probe card is replaced and/or repaired only after a
failure has occurred. This results in undesirable system down
time.
The problem of maintaining records on individual probe cards is
made difficult by the fact that probe cards are frequently moved in
and out of a testing system as described above. One solution
involves manually labelling the various probe cards, and manually
entering information regarding probe card usage on data sheets or
into a computer. Unfortunately, this becomes difficult or
impractical when large numbers of probe cards are in use.
Additionally, the procedure is highly susceptible to human
error.
Systems which present specific solutions to the above-described
problems are disclosed in commonly assigned U.S. Pat. No. 5,254,939
for PROBE CARD SYSTEM AND METHOD, commonly assigned, copending U.S.
patent application Ser. No. 08/089,874, filed on Jul. 9, 1993, now
abandoned, as a continuation of the '939 patent, and commonly
assigned, copending U.S. patent application Ser. No. 08/183,596,
filed on Jan. 19, 1994, now abandoned, the entire specifications
and drawings of which are herein incorporated by reference. The
systems described in these documents provide excellent solutions to
the above-described problems. However, because of specific industry
needs, other solutions are needed.
In view of the foregoing, an improved system and method for
conducting wafer probe tests is needed which provides a sturdy,
simple, quick and reliable interface to load probe cards under a
test head. An improved system and method for tracking individual
probe card usage and performance as well as its alignment position
under the test head is also desirable.
SUMMARY OF THE INVENTION
According to the present invention, an improved wafer testing
method and prober to test head interface system is provided. The
system, also referred to hereinafter as the "AutoLoader" provides
for convenient loading and changing of probe cards, as well as a
more effective means for positioning probe cards during test
operations. The present invention is also directed to a systematic
method and device for probe card data collection.
According to one embodiment, a prober to test head interface system
is provided which includes a stiffener for holding a probe card,
the stiffener having an upper surface, a perimeter, an underside, a
plurality of recesses in the underside around the perimeter, and
first and second alignment holes. The system also includes a theta
ring for holding the stiffener, the theta ring having first
alignment pins for engaging the first alignment holes, a plurality
of lock cylinders for engaging the recesses, and a machined lip
against which the upper surface of the stiffener is forced by the
lock cylinders. A loader is coupled to the prober for loading the
stiffener in and unloading the stiffener from the theta ring, the
loader having second alignment pins for engaging the second
alignment holes. A theta drive assembly is coupled to the theta
ring for rotating the theta ring to align the probe card with the
wafer. In a specific embodiment, the test head comprises a
contactor, and the theta ring includes a plurality of clamp
cylinders for locking the contactor in theta and Z while a probe
card is being loaded or unloaded.
The present invention includes both manual and automatic
embodiments. In one manual embodiment, the loader is an arm
assembly which employs an articulated arm having a plurality of
segments to position the stiffener in the prober. A hand is coupled
to the arm for holding the stiffener, the second alignment pins
being located on the hand. A handle is coupled to the arm
facilitating manual manipulation of the arm assembly, and thereby
positioning of the stiffener in the prober.
In an automatic embodiment, the loader is an arm assembly which
automatically moves the stiffener in first and second directions,
the first direction being substantially parallel to the plane
defined by the upper surface of the stiffener, and the second
direction being substantially perpendicular to the upper surface
plane. The arm assembly includes a Z mechanism coupled to the
prober. A first slide assembly is coupled to the Z mechanism. A
first air cylinder is coupled to the first slide assembly. A second
slide assembly is coupled to the first air cylinder. A second air
cylinder is coupled to the second slide assembly. A hand is coupled
to the second air cylinder for holding the stiffener, the second
alignment pins being located on the hand. The first air cylinder
moves the second slide assembly with respect to the first slide
assembly in the first direction. The second air cylinder moves the
hand with respect to the second slide assembly in the first
direction to a position directly below the theta ring. The Z
mechanism moves the arm assembly in the second direction, thereby
causing the first alignment holes to engage the first alignment
pins on the theta ring
Each of the above described embodiments may also include a touch
memory associated with, attached to, or embedded in the stiffener.
The touch memory stores a variety of operational data regarding the
probe card held in the stiffener. When the touch memory comes into
contact with a memory reader, operational data may be read from and
written to the touch memory. In one manual embodiment, a memory
reader on the hand makes contact with the touch memory when the
stiffener is loaded on the hand. In an automatic embodiment, a rack
of stiffener storage shelves has a memory reader on each shelf.
When the arm assembly replaces a stiffener on one of the shelves,
the memory reader on that shelf makes contact with the touch
memory.
A further understanding of the nature of the invention may be
realized by referring to the remaining portions of the
specification and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a system block diagram of a wafer test system
incorporating an AutoLoader designed according to the present
invention;
FIG. 2 is a perspective view of one embodiment of the present
invention;
FIG. 3a is a perspective view of a theta ring assembly in one
embodiment of the invention;
FIG. 3b is a bottom view of a probe card stiffener;
FIG. 3c is a bottom view of the theta ring assembly;
FIG. 4a is a drawing of the stiffener transport assembly for one
embodiment of the invention;
FIG. 4b is a top view of the stiffener transport assembly in its
storage position;
FIG. 5 is a perspective view of another embodiment of the
invention;
FIG. 6 is a different view of the embodiment of FIG. 5;
FIG. 7 depicts the probe card stiffener transport assembly and
storage rack according to one embodiment of the invention;
FIG. 8 illustrates the position of the stiffener rack in one
embodiment for facilitating replacement of probe card
stiffeners;
FIGS. 9-13 illustrate a process for operating the AutoLoader 3M in
a series of logical flowcharts; and
FIGS. 14a, 14b-18 illustrate a process for operating the AutoLoader
3A in a series of logical flowcharts.
DESCRIPTION OF SPECIFIC EMBODIMENTS
Two specific embodiments of the method and apparatus of the present
invention are described herein with reference to the
above-described figures. A manual embodiment will be described
first with reference to the terms defined below.
FIG. 1 is a system block diagram of a wafer probe system
incorporating an Autoloader designed according to either of the
embodiments of the present invention described below. The system 2
includes a prober 4, which includes the prober to test head
interface (AutoLoader) assembly 6. Prober 4 contains mechanical
elements for moving wafers into position for testing, and various
associated testing and control electronics of the type known to
those of skill in the art. Autoloader 6 serves as an interface
between prober 4 and a test head 8.
Attached to test head 8 is a floating contactor assembly, commonly
referred to in the industry as a "Pogo stack" (not shown). The
floating contactor comprises "Pogo pins" which make contact with
the wafer probe card being used, and are the means by which signal
are applied to and data retrieved from the probe card. In order to
be coupled to the Pogo pins, the probe card must be positioned with
respect to test head 8. When in position, the probe card, with
probing points extending downwards, is then made to make contact
with a wafer (not shown) and appropriate signals are applied
thereto. The responses of the various dies on the wafer are then
monitored and recorded.
Test head 8 is connected by various conductors 10 to a tester 12.
Tester 12 contains the necessary computer processing facilities to
direct the application of test signals to the wafer or device under
test (DUT), and further to record and interpret the responses of
the wafer to the signals.
In specific embodiments of the present invention, the
prober-to-test head interface system comprises a transport assembly
which positions the probe card stiffener into a working test
position. The "AutoLoader 3M" facilitates the manual loading and
unloading of probe cards. A prober 200 with loading arm 202
attached thereto is shown in FIG. 2.
The following terms will be defined with reference to FIGS. 2-4.
The "arm" 202, shown in FIG. 2, allows manual loading and unloading
of probe card stiffeners into prober 200, through a door in the
left side of the prober. Attached to the end of the arm is a "hand"
204. Behind hand 204 is the assembly of handle 244 and the arm
alignment tubes 206 which are used together to align arm 202 to the
docking pins 208 on the left side of the ring carrier 210. Arm 202
resides next to the system controller 212 and both are attached to
the mounting plate 232 which is bolted to the prober frame. The
joints 214 in arm 202 provide the freedom of motion needed to
insert and retrieve probe card 216 in its stiffener 218 into and
from "theta ring" 222. The joints 214 are attached to the shoulder
215 for adjustments in pitch, roll and Z.
The "contactor" (not shown) is an electromechanical device
responsible for test signal transmission through probe card 216 to
the device under test (DUT). The contactor uses coaxial cable, Pogo
pins, and the probe card itself as the transmission elements.
The "control panel" 217 is the user interface for the AutoLoader 3M
which is connected to the system controller 212. It displays menus
and options on an LCD 217a with two lines of 40 characters each.
The control panel has a four pushbutton keypad 217b with indicator
lights to aid in the selection process and a theta adjust knob
217c.
Referring now to FIG. 3a, the "contactor clamp cylinders" 220 are
three air-driven clamps which are used to lock the contactor in
theta and Z during a probe card swap.
The "contactor guide pins" (not shown) are three pins which
protrude from the prober side of the contactor to align the
contactor to the probe card.
The "die interface" (not shown) comprises tungsten probes or
membrane "bumps" which make physical and electrical contact to the
device under test.
Referring now to FIG. 4a, the "hand" 204 is attached to the end of
arm 202 and carries probe card stiffener 218 between the theta ring
222 and the outside of prober 200 (see FIG. 2). It has three
adjustable pins 224 which insert into stiffener 218 for alignment
and leveling. It also includes a touch memory read/write station
226. FIG. 4b shows the arm assembly in its storage position against
the side of prober 200.
Referring back to FIG. 2, the "ring carrier" 210 is the top plate
of prober 200, and contains the interface to the test head and the
theta drive 228.
The "stiffener" 218 mounts to and provides structural stiffness to
probe card 216. A touch memory 219 is permanently attached to the
bottom of each stiffener 218 as shown in FIG. 3b, a bottom view of
stiffener 218. Stiffener 218 also has a several recesses 225 in its
underside around its perimeter.
FIG. 3c shows a bottom view of theta ring 222. The "stiffener lock
ram cylinders" 221 are air cylinders facing inward around the
periphery of theta ring 222, used to lock stiffener 218 in the
working position in theta ring 222. Rollers 223 on the end of the
air cylinder shafts provide non-galling contact with the stiffener
at recesses 225.
The "system controller" 212 is a PC-clone-based controller which is
bolted to the left side of prober 200.
The "theta drive assembly" 228 is a stepper motor assembly which
rotates probe card 216 in order to align the probe tips to the
device under test pads. Theta drive assembly 228 of the present
invention allows for fast probe-to-pad alignment by recalling theta
offset data from previous uses of a specific probe card stored in
the touch memory. Operators can also manually set the theta angle
by rotating the theta adjust knob on the control panel. The new
theta offset adjustment will be automatically stored in the touch
memory for the next time the probe card is used.
The "theta ring" 222 is the adapter between ring carrier 210 and
stiffener 218 which provides for the theta orientation of probe
card 216.
The "theta offset" is the difference in angular orientation probe
card 216 between its working location where it is properly aligned,
and the orientation at which it is inserted into theta ring 222.
The theta offset is stored in the touch memory and can be recalled
and automatically corrected each time a probe card is loaded.
The "touch memory" 219 is a watch-battery-sized device which
contains a real-time clock and 4,096 bits (512 bytes) of
non-volatile RAM. The touch memory is used to store probe card
usage information, and is mounted on the lower surface of stiffener
218, flush with the stiffener's bottom.
The "touch memory read/write station" is located on hand 204 and
makes electrical contact with the touch memory for serial
communications with system controller 212.
The "wrist" 230 (FIG. 4a) is coupled to arm 202 and accommodates an
anti rotation pin mounted in handle 244 (not shown) which secures
the handle in the load/unload position. This pin is spring loaded
and can be disengaged from the wrist for rotating the handle to
parallel position with respect to the arm during storage.
The "X", "Y", "Z", and "theta" directions are relative to the
center of the probe card as viewed from the front of the prober.
Positive "X" is motion to the right; positive "Y" is motion away
from the operator; positive "Z" is vertical motion up from the ring
carrier, and "theta" is angular motion around the Z-axis.
The system comprises the following subsystems. The arm assembly
comprises arm 202 and hand 204. Arm 202 is mounted on a shoulder
215 which is bolted to the prober frame. shoulder 215 has pitch and
roll adjustments (.+-.3 degrees for each), as well as a one quarter
inch "Z" adjustment. Arm 202 consists of three links 234 which
allow manual alignment of probe card stiffener 218 into ring
carrier 210. Handle 244 has 90 degrees of rotation to allow for
storage (FIG. 4b), but has a spring loaded pin to positively lock
it into position. Hand 204 has approximately 11/4" of air powered
"Z" travel, riding on a linear bearing for guidance. Hand 204 is
affixed to the end of arm 202 and moves with it. Hand 204 has three
pins 224 which hold probe card stiffener 218 in the correct
orientation while being transported. There is a touch memory read
station 226 (see FIG. 2) on hand 204 for communicating with touch
memory 219 mounted on the bottom of stiffener 218. Arm 202 and hand
204 are designed to accommodate the combined weight of probe card
216 and stiffener 218.
Stiffener 218 is an anodized aluminum device which is affixed to
probe card 216. Alignment of probe card 216 to stiffener 218 is
established by two close-tolerance pins which are pressed into
stiffener 218 and pass through two close-tolerance holes in probe
card 216. Stiffener 218 carries a touch memory affixed thereto
which contains the history, the theta offset, and any other
pertinent data regarding probe card 216 stored therein. Stiffener
218 has six close-tolerance alignment holes 236, three of which are
used to position stiffener 218 relative to hand 204, and three of
which are used to align stiffener 218 with theta ring 222.
Stiffener 218 also has close-tolerance holes which engage guide
pins on the contactor, thereby aligning the contactor assembly to
probe card 216.
Theta ring 222 resides in the central hole in ring carrier 210. It
defines the location in "X", "Y", theta, and "Z" for stiffener 218,
and provides mounting for contactor clamp cylinders 220. The
stiffener lock ram cylinders 221 (FIG. 3c) are built into the lower
edge of theta ring 222. Close-tolerance pins 238 in theta ring 222
provide the "X", "Y" and theta alignment of stiffener 218 to theta
ring 222. The Z-stop 240 is a machined lip in theta ring 222,
against which stiffener 218 is forced by the stiffener lock ram
cylinders 221.
The Theta drive 228 has a motorized metal belt drive which provides
the force needed to rotate theta ring 222 around the test head
Z-axis (i.e., in theta). The theta drive belt is connected to theta
ring 222 by a single screw (not shown). Theta drive assembly 228
includes the theta drive frame, the theta drive motor with encoder,
the theta drive cover, the drive assembly and the theta drive
electronics. The stiffness of ring carrier 210 is not adversely
affected by the cut-out in which theta drive 228 is disposed. The
operation of theta drive assembly 228 is as follows. Once the
operator has pushed the "Load" button, controller 212 instructs the
theta motor to turn in a specified direction until the theta drive
position feedback encoder reports that theta ring 222 is aligned
with the zero position (i.e., 0 m). Probe card stiffener 218 is
installed by arm 202. The theta offset correction necessary for
that particular probe card (information which was collected
automatically upon last use of the probe card) is made without
operator intervention. This provides rough probe-to-pad
alignment.
Once the load process is complete the operator has the option of
using the theta adjust knob on the control panel to turn theta
drive 228, thereby turning theta ring 222, and thus probe card
stiffener 218, to align the die interface with the device under
test (DUT). There is an encoder which monitors the shaft on the
theta motor to ensure positive positioning. The unload sequence is
initiated by the operator pushing a button on the control panel to
start the process. System controller 212 once again interacts with
theta drive assembly 228 to drive it to the zero position. After
the unload sequence is complete the theta motor is inoperative
until the load sequence is initiated again.
System controller 212 consists of an IBM PC-Clone motherboard with
an IDE hard/floppy disk and a dual serial port/single parallel port
adapter cards; two 24 point digital I/O cards; a 256 k VRAM VGA
card; an IEEE-488 adapter card; and a single channel Quadrature
Encoder Input Card. There are two separate power supplies in the
controller; one for the PC motherboard and one to supply power for
I/O and the stepper motors. All inputs to the PC are via
opto-coupled circuitry, including communications links. All grounds
are tied to a common frame point. The power coming into system
controller 212 is RF-filtered with an industrial-grade filter
network. Space is provided for solenoid-driven air control valves
to control the pneumatic devices which move portions of the
AutoLoader. System controller 212 has at least 10% extra,
undedicated I/O, sufficient to handle both the current and future
needs of the Autoloader. There is a guarded ON/OFF switch on the
front face of controller 212.
The user interface for the AutoLoader is the control panel which
has an LCD display, four pushbuttons, and a theta knob switch.
Error messages will be sent over the IEEE 488 interface to the
prober CRT. Testing and trouble shooting is facilitated by the
capability of tying directly into the Autoloader controller with a
keyboard and VGA screen.
To dock the test head to prober 200, a probe card 216 mounted in a
stiffener 218 must be in place in theta ring 222. The test head is
moved with the manipulator arm provided by the manufacturer to the
correct location in X, Y and theta for docking. The test head is
lowered until contact with probe card 216 has been achieved, as
verified by the contactor sensors. The contactor vacuum is then
turned on, and the contactor is pulled down onto probe card 216,
compressing the utility and signal pins.
Once the test head contactor is docked, probe card 216 and
stiffener 218 may be removed in the following manner. First, the
operator pushes the lighted "Unload" button on the control panel.
The AutoLoader asks (over the IEEE-488 link) if the tester is
currently running a testing program. If it is not, the AutoLoader
sends a command to prober 200 to move the forcer [chuck] to a safe,
out-of-the-way position. If the tester is testing, the operator
will be informed that the tester is not willing to relinquish
control at this rime, and the AutoLoader will return to its "test
program running" mode. If the tester is not testing, theta drive
228 rotates theta ring 222 from the last theta offset position to
the theta zero position. The AutoLoader will request that the
tester turn off the contactor vacuum. This allows the utility and
signal pin forces to drive the contactor up, off of probe card 216.
The vacuum seal foam gasket will still be sufficiently compressed
to allow re-application of vacuum.
When the tester confirms that the vacuum has been turned off,
contactor clamp cylinders 220 are extended, locking the contactor
in "Z" and theta. At this point in the process the contactor guide
pins are still engaged in stiffener 218, so it (the contactor)
cannot move out of alignment. The control panel then displays a
message letting the operator know it is safe to proceed, and a
green light on the side of controller 212 comes on. The operator
unfolds arm 202 from its storage position, and rotates the hand
"finger" 242 to its working orientation. The operator then grasps
the handle 244 on the arm assembly and pushes the hand through the
prober left side door until the alignment tubes 206 on the handle
dock against two alignment pins 208 attached to ring carrier 210.
Hand 204 (and thus probe card 216 and stiffener 218) will now be
positioned under theta ring 222.
The AutoLoader detects that the arm assembly is in position to
remove probe card 216 when switches 209 at the base of docking pins
(one each) are tripped by the alignment tubes. The green lamp turns
off the and the red lamp turns on, thereby warning the operator to
wait and not move anything. The "Z" cylinder 247 in the arm "wrist"
area lifts hand 204 up to the bottom of probe card 216. The
stiffener ram lock cylinders (not shown) retract, releasing
stiffener 218 onto hand 204. Hand 204 moves in the "Z" direction,
removing probe card stiffener 218 from the interface. The touch
memory is updated with usage and theta offset information by the
touch memory read station. If this writing process is successful,
the green lamp comes on, telling the operator that it is safe to
remove the probe card from the hand. The operator pulls on handle
244 to bring the arm assembly back outside the prober left side
door.
If the write process is unsuccessful, the yellow light flashes and
the operator has to read the touchdown data from the control panel
display and write it down. The operator will be given the
opportunity to clean the touch memory contact surface and replace
the probe card on the hand for another try at writing the data.
Once a successful data write cycle occurs, the operator removes the
probe card from the hand and stores the arm assembly against the
left side of the prober unless the operator wishes to load another
probe card.
A probe card 216 may be loaded in prober 200 in the following
manner. This procedure assumes that the test head/contactor is
already docked. The operator first pushes the lighted "Load" button
on the remote control. The control panel displays a message telling
the operator that it is safe to proceed. A green lamp lights on the
controller adjacent the arm storage area. The operator unfolds arm
202 and rotates finger 242 and handle 244 to the working position.
The operator then places probe card stiffener 218 on hand 204,
automatically making the connection between touch memory read
station and the touch memory mounted on the bottom of probe card
stiffener 218. The touch memory read station polls the touch memory
for the probe card serial number, usage data, and theta offset
information which it temporarily stores in the RAM of the
controller. If the data is not read successfully, the yellow light
will flash, informing the operator that the read cycle was not
completed successfully.
Once a successful read of the touch memory has been achieved, the
operator grasps handle 244 on the arm assembly and pushes the hand
through the prober left side door until the alignment tubes 206 on
the arm docks against two alignment pins 208 attached to ring
carrier 210. Hand 204 and probe card stiffener 218 are then
perfectly positioned under theta ring 222. The AutoLoader 3M
detects that the arm assembly is in position to insert a probe card
when two switches 209 at the base of the alignment pins (one each)
are tripped by the alignment tubes. The green lamp turns off and
the red lamp turns on warning the operator to wait, and not to move
anything. The AutoLoader retracts the ram lock cylinders 221, and
engages the "Z" cylinder 247 on arm 202 to lift probe card
stiffener 218 up into the interface.
When stiffener 218 is detected as being in place by a fiber-optic
sensor in theta ring 222, the ram lock cylinders (not shown)
extend, locking probe card stiffener 218 into place. "Z" cylinder
247 is then retracted (i.e., lowered), and the red lamp is turned
off and replaced by the green lamp. Contactor clamp cylinders 220
then retract, freeing the contactor to move in "Z". The operator
pulls the arm assembly out of the prober and folds it against the
left side of the prober. The AutoLoader tells the tester to turn on
the vacuum. The theta drive then rotates the theta ring to the
theta offset position retrieved from the touch memory during the
load cycle.
The "AutoLoader 3A", a different embodiment of the present
invention, is for the automatic mechanized loading and unloading of
probe cards. The Autoloader 3A has a magazine capable of holding
two (or more) probe cards, and will be described with reference to
FIGS. 5-8. A prober 400 with the magazine 402 attached thereto by
docking hardware 404 is shown in FIG. 5.
The following terms will be defined with reference to FIGS. 6 and
7. The "arm" 406 carries the probe card 408 and the stiffener 410
between the prober 400 and the magazine 402. Arm 406 is attached to
the magazine frame 412. The extension/retraction function of arm
406 is driven pneumatically. Arm 406 has a relatively small amount
of "Z" motion capability which is used to transfer stiffener 410
between a hand 414 and a theta ring 416. "Z" motion is provided by
a stepper-motor-driven screw (not shown).
The "contactor" (not shown) and "contactor clamp cylinders" 418 are
as described above with reference to the Autoloader 3M.
The "die interface" (not shown) comprises probe pins or membrane
"bumps" which make physical and electrical contact to the device
under test.
The "hand" 414 is attached to the end of arm 406, and carries probe
card stiffener 410 between the theta ring 416 and a rack 422. Hand
414 has three pins 424 which insert into stiffener 410 for
alignment. Hand 414 and arm 406 form the arm/hand assembly 426.
The "magazine" 402 contains arm/hand assembly 426, rack 422, a
system controller (401),. Magazine 402 is mounted on wheels and
docks to the ring carrier 432 and prober 400. Separate umbilicals
provide electrical, pneumatic, and digital connections between
magazine 402 and prober 400.
The "motorized (stepper motor) probe card theta" or "theta drive"
434 rotates probe card 408 in order to align the die interface to
the pads on the device under test. It allows for faster
probe-to-pad alignment by recalling theta offset data from previous
uses of a particular probe card recovered from a touch memory
embedded in stiffener 410. Operators can also manually set theta
angle by pushing buttons on the prober keypad.
The "rack" 422 is a storage area for probe cards 408 within
magazine 402. Rack 422 has sufficient "Z" travel to permit arm 406
to come in under the next probe card which is to be carried into
prober 400, and to then place the probe card onto hand 414. The "Z"
motion is provided by a rack Z-drive 436 comprising a
stepper-motor-driven screw which turns in a nut located in the
moving portion of the rack.
The "rack shelf" 438 holds individual stiffeners 410. Each shelf
has a touch memory read/write station on its upper surface (not
shown).
"Ring carrier" 432, "stiffener" 410, "stiffener lock ram cylinders"
(not shown), "system controller" 401, "theta ring" 416, the "theta
offset", the "touch memory", the "touch memory read/write station",
and the "X", "Y", "Z", and "theta" directions are substantially the
same as described above with reference to the Autoloader 3M.
The Autoloader 3A system comprises the following subsystems. The
transport assembly (shown in FIG. 7) comprises arm 406, rack 422,
and hand 414, and is mounted inside magazine 402. The structure and
operation of the transport assembly limits the potential for probe
needle damage. Arm 406 consists of two air cylinder driven slides
442 and 444, mounted to one another to provide a telescoping action
to move probe card stiffener 410 from magazine 402 into prober 400
and back. A stepper-motor-driven screw and nut combination (not
shown) gives arm 406 the ability to move approximately 1" in the
"Z" direction. This motion is used to place probe card stiffener
410 into the theta ring 416.
Rack 422 has two shelves 438 on which probe card stiffeners 410 are
stored. Each shelf 438 has a touch memory read/write station for
communicating with the touch memory mounted on stiffener 410. Each
shelf 438 has three pins 446 which provide repeatable alignment of
probe card stiffener 410.
Rack 422 has sufficient "Z" travel to allow the hand-off of probe
card stiffeners 410 from either of rack shelves 438 onto hand 414.
This "Z" travel is driven by a motor-screw combination 436 similar
to that used for arm 406.
Hand 414 is affixed to the end of arm 406 and moves with it. Hand
414 has three pins 424 which hold probe card stiffener 410 in the
correct orientation while being transported between magazine 402
and prober 400. Arm 406 and hand 414 must be designed to
accommodate the combined weight of the combination of probe card
408 and stiffener 410.
The stiffener/probe card assembly is substantially the same as
described with reference to the Autoloader 3M.
Theta ring 416 resides in a central hole in ring carrier 432 (see
FIG. 6). The purpose and function of theta ring 416 is
substantially the same as described above with reference to
Autoloader 3M.
The theta drive assembly 434 has a motorized metal belt drive which
provides the push and pull needed to rotate the theta ring around
the test head "Z" axis; i.e., in theta. The operation is as
follows: Once the operator has pushed a prober keypad "hot key" to
start a load sequence, or an IEEE-488 command has been received
from the tester, the controller instructs theta motor 430 to turn
in a specified direction until the theta drive position feedback
encoder reports that theta ring 416 is aligned with the "home" or
zero degree position. Probe card stiffener 410 is then installed
using arm 406, as described below. The theta offset correction
necessary for that particular probe card (information which was
collected automatically upon first use of the probe card, and is
automatically updated after each use) is made without operator
intervention. This will provide probe-to-pad alignment. Once the
load process is complete, the operator has the option of using the
"hot key" push buttons on the prober keypad to turn theta drive
434, thereby turning theta ring 416 (and thus, probe card stiffener
410) to align the die interface with the device under test. The
unload sequence can be initiated by either the operator by pressing
a "hot key" on the prober keypad to start the process, or the
tester over the IEEE-488 interface. The controller once again
interacts with theta drive 434 to find the "home" position. After
the unload sequence is complete, theta motor 430 remains
inoperative until the load sequence is initiated again.
The theta drive assembly consists of the theta drive frame, the
theta drive motor and the theta drive cover, the driver assembly,
the theta drive connection (on the side of the ring carrier) and
the theta drive electronics. As with the 3M embodiment, the
stiffness of ring carrier 432 will not be adversely affected by the
pockets necessary for the theta drive or the theta drive position
feedback encoder.
The system controller is substantially the same as the controller
described with reference to the 3M embodiment. Additionally, the
user interface for the AutoLoader 3A is integrated into the RTM
software running on the prober (controlling the user's
interface/display). The AutoLoader communicates with RTM over a
dedicated serial link. RTM will respond to dedicated "hot keys" on
the prober keyboard, and send commands down the serial link to the
AutoLoader 3A controller. One "hot key" will place RTM in a special
terminal emulator mode, wherein the AutoLoader controller will take
over all but the last two lines of the 25-line prober screen. In
this mode, the following screens will be available: the Xandex Main
Menu allows selection of the following screens, as well as displays
the current theta offset, and enables keyboard-driven theta
adjustment, probe card load, and probe card unload: the System
Setup screen, the Diagnostics screen, and the Display Touch Memory
screen.
Magazine 402 contains the stiffener transport assembly 426 and the
controller 401. It is on spring-loaded casters, and has
powder-coated external sheet metal. The sheet metal has been styled
to have an appearance compatible with the prober design. There is
an internal square tubular frame to which all major components are
anchored. The magazine is docked to the ring carrier via two
spring-loaded docking pins. Two bayonet-style rotating receptacles
404 affixed to the magazine will lock to these pins. A third
connection from magazine 402 to prober 400 is made to a point lower
on the prober frame. This connection can be moved either closer or
farther away from the magazine, thus rotating magazine 402 about a
line passing through the upper docking pins. This allows for
manufacturing variations from prober to prober, and fine alignment
of the transport mechanism arm 406 and hand 414 to the theta ring
416. This adjustment will be retained when the magazine is pulled
away and then restored to its docked position against the prober,
and therefore needs only be made once per prober/magazine
combination.
To dock the test head to prober 400, a probe card 408 mounted in a
stiffener 410 must be in place in theta ring 416. Prior to docking,
the contactor clamp cylinders 418 are in their normal retracted
state. The test head is lowered down into the interface. The
contactor is moved with the manipulator provided by the
manufacturer to the correct location in "X", "Y" and "theta" for
docking. The test head is lowered until contact with probe card 408
has been achieved, as verified by contactor sensors. The contactor
vacuum is then turned on, and the contactor is pulled down onto
probe card 408, compressing the utility and signal pins.
A loaded probe card is replaced in the Autoloader 3A embodiment in
following manner. Arm 406 moves out of magazine 402, pushing the
prober side door open, and positioning hand 414 below stiffener
410. Simultaneously, theta ring 416 rotates to the 0.degree. or
"home" position. Arm 406 and hand 414 then move up in "Z" and
engage stiffener 410. Theta ring 416 releases stiffener 410 (with
probe card 408 attached) onto hand 414. Arm 406 and hand 414 then
lower stiffener 410 down, out of theta ring 416. As this is taking
place, rack 422 moves in "Z" to align empty probe card shelf 438
with incoming probe card 408.
Once stiffener 410 and probe card 408 are in place, securely
mounted on hand 414, arm 406 retracts into magazine 402, inserting
stiffener 410 and probe card 408 into the waiting empty slot in
rack 422. Rack 422 moves up in "Z", lifting stiffener 410 and probe
card 408 off of hand 414. When electrical contact has been made
with the touch memory (mounted on the bottom of the stiffener), the
touch memory is updated with the latest touchdown and other
information. Once communication has been established between the
Autoloader 3A controller and the touch memory, a green light on the
outside of the magazine (one per rack shelf) lights, providing
confirmation. Arm 406 then moves into prober 400, clear of rack
422.
Rack 422 moves again in "Z" to align the hand with the other
stiffener 410 in rack 422. Arm 406 moves back into magazine 402,
and rack 422 places the other probe card stiffener 410 onto hand
414 by moving in "Z". Arm 406 then moves into prober 400 carrying
probe card stiffener 410 on hand 414. At the end of the arm's
travel, arm 406 and hand 414 move in "Z" to insert probe card
stiffener 410 into theta ring 416. Theta ring 416 locks in
stiffener 410, at which point arm 406 and hand 414 move down in
"Z", and retract into magazine 402, storing hand 414 inside
magazine 402 in the empty rack shelf 438 where the probe card
currently in use previously resided. As arm 406 and hand 408
retract into magazine 402, the prober side door closes.
During the above-described procedure, the theta ring assembly and
transport assembly components perform the following actions. Theta
drive 434 rotates theta ring 416 from the theta offset position for
the loaded stiffener to the 0.degree. position. The contactor
vacuum is turned off, allowing the utility and signal pin spring
forces to drive the contactor up, off of probe card 408. Contactor
clamp cylinders 418 extend, locking the contactor in theta. At this
point, the contactor guide pins are still engaged in stiffener 410
so it cannot move out of alignment.
Arm 406 moves out of magazine 402, as described above, to a
position underneath theta ring 416. Hand 414 is brought up in
contact with the bottom of stiffener 410. Stiffener lock ram
cylinders (not shown) retract, releasing stiffener 410 onto hand
414. Arm 406 and hand 414 lower stiffener 410 down, out of theta
ring 416, and carry it away. Probe card stiffener 410 is dropped
off in rack 422, as described above, and the other stiffener 410 is
picked up. The new stiffener 410 is brought out of magazine 402,
into prober 400, and lifted up into theta ring 416 by hand 414.
Guide pins in theta ring 416 engage matching holes in stiffener
410, aligning it in "X", "Y" and "theta". The stiffener lock ram
cylinders (not shown) extend, forcing stiffener 410 up against the
Z-stop surface of the theta ring, compressing the foam vacuum
gasket of the contactor. Hand 414 then lowers and arm 406 retracts
into magazine 402.
Contactor clamp cylinders 418 then retract, freeing the contactor
in theta. The contactor vacuum is turned on, compressing the
utility and signal pins, and locking down the contactor to probe
card 408. Theta drive 434 rotates theta ring 416 to the theta
offset (stored in the touch memory) for the loaded probe card.
If the operator wishes to change out both probe cards in the
magazine, the Xandex Menu Window is brought up on the prober
display, and the operator initiates the Unload Probe Card sequence.
The operator must confirm that the AutoLoader 3A has finished the
operation before opening the magazine door by observing either the
prober display or the flashing yellow light on the magazine (the
light flashes when the AutoLoader 3A is busy). If the AutoLoader 3A
is in operation, and the door is opened, the process underway is
brought to a stop as quickly as possible. Recovery from this
emergency stop (E-stop) state begins when the door is closed.
When the operator opens the door, rack 422 extends out of magazine
402 automatically to a position as shown in FIG. 8. This only
happens as a consequence of having initiated the Unload Probe Card
sequence. At this point, any probe card in the rack can be removed
or installed as needed. As noted above, a lamp on the outside of
the magazine provides visual feedback that the stiffener is
correctly in place in its respective rack shelf, and that
communication has been established with the touch memory on the
bottom of the stiffener. Once the probe card replacement is
complete, the operator pushes a button inside the cabinet to
retract the rack, and closes the magazine door once the rack is
fully inside.
As described above, the system and method of the present invention
also comprise a probe card data collection system. In a specific
embodiment, the individual probe cards are each provided with a
corresponding memory. The memory is both writable and readable. The
memory is mounted in a depression on the underside of the probe
card stiffener in which the corresponding probe card is mounted.
The memory may comprise erasable memory such as static random
access memory (SRAM), or dynamic random access memory (DRAM) backed
up by a power source, e.g., a battery. It should be apparent that
write-only memories also may be used in some embodiments. In the
embodiments described herein, the memory comprises a serial touch
memory.
Since the touch memory is coded to an individual probe card, probe
card performance and usage data may be easily tracked. It will be
apparent that a wide variety of storage devices may be used without
departing from the scope of the invention.
A variety of operational data about the probe card in the loader
may be written to memory from a controller which is located in the
transport assembly, via a touch memory data transfer device. Table
1 lists various types of operational data which may be recorded in
the memory cell along with the source of the data.
TABLE 1 ______________________________________ Operational Data
Source of Data ______________________________________ Touchdowns
Loading assembly Serial number Input @ PC maint. station Date of
last maintenance Input @ PC maint. station Date of manufacture
Input @ PC maint. station Failure nature of probes GPIB-tester
Location of failed probes GPIB-tester Operators' I.D. Loading
assembly Scheduled maintenance date Input @ PC maint. station
Scheduled maintenance touchdowns Input @ PC maint. station Previous
theta location Input @ PC maint. station
______________________________________
In one embodiment, a real time clock is incorporated into the key
element for recording the times at which the corresponding probe
card is used, as well as for recording the times when the probe
card is checked or repaired.
The memory described herein with respect to various embodiments of
the invention is useful for storing information about the number of
times a particular probe card has made contact with wafers
(touchdowns) since it was last serviced. Other important
information which may be stored in the memory includes the number
of failed contacts of individual or groups of probes and their
locations, the probe card serial number, the date of the card's
last maintenance, or the like. The memory feature described herein
allows the system user to read maintenance information for a
particular probe card, thereby enabling the user to identify probe
cards which have been used extensively or which have exhibited
unacceptable failure rates. In this way, probe cards which should
be serviced or replaced may be easily identified.
In FIGS. 9-13, a process for operating the Autoloader 3M is
depicted in a series of logical flowcharts. At step 500 in FIG. 9,
a power up sequence is initiated after which a system test is run
at step 502. If any errors are detected in the system test, an
error message is displayed and system operation is suspended. If no
errors are detected, the system checks to see whether a stiffener
is currently present in the prober (step 510). If a stiffener is
present, a loaded flag indicating the presence of the stiffener is
set. If no stiffener is present, the loaded flag is cleared. The
system then clears both the load request and the unload request
flags at step 516. At step 518, the system decides which of two
menus to present to the operator. If the loaded flag was set at
step 512, the system runs the run menu routine illustrated in FIG.
10. To begin the run menu routine, the system displays the message
of step 552 which gives the operator the option of unloading the
stiffener, reading the operational data for the loaded probe card,
or adjusting the angular position of the theta ring with the theta
adjust knob. The system then checks for movement of the theta
adjust knob in either the clockwise or counter-clockwise
directions, moving the theta ring accordingly. If the operator
pushes button #4, the system displays and scrolls the stored
operational data (steps 562 and 564). If the operator pushes button
#2, the system sets the unload request flag and returns to the
previous routine (FIG. 9).
If the loaded flag was cleared at step 514, the system runs the
main menu routine (FIG. 11), which presents a message to the
operator giving the option of loading a stiffener or aligning the
system for installation (step 602). If the operator chooses the
former and pushes button #1, the system sets the load request flag
and returns to the previous routine illustrated in FIG. 9 (steps
604-608). If at step 610, the operator pushes button #3, thereby
choosing the latter option, the system performs a system
installation alignment at step 612. The system then waits for
either button #1 or #3 to be pressed.
Once either the load request flag or the unload request flag has
been set as described above, the system checks to see which flag
has been set (step 518 of FIG. 9). If the load request flag has
been set, the system performs the load probe card routine of FIG.
12. The system first checks for air pressure and then tells the
prober to secure the test head for loading (steps 652 and 654). At
step 656, the system prompts the operator to place a stiffener and
probe card on the transport hand. The system then checks for the
presence of the touch memory for the next 30 seconds, after
which
time, if no touch memory is detected, the system displays a message
asking the operator if a stiffener has been placed on the hand. If
the operator responds affirmatively, an error message is displayed
and system operation is suspended (steps 658-666). If the operator
responds negatively, the system checks for the presence of a touch
memory for another 30 second period. Once the touch memory is
detected, the system reads the operational data stored in the touch
memory at step 668. The system then checks to see whether the
cyclic redundancy check (CRC) is OK. If not, an error message to
that effect is displayed, and system operation is suspended (steps
670-674). If the CRC is OK, the operator manually moves the
articulated loading arm assembly into position below the theta ring
at which point the system moves the arm vertically and loads the
stiffener into the theta ring (step 676). The system then sets the
touchdown count to zero, notifies the operator that the particular
probe card has been loaded, sets the loaded flag, and clears the
load request flag (steps 678-682).
If the unload request flag has been set, the system performs the
unload probe card routine of FIG. 13. The system first checks to
see that air pressure is present (step 702). Then, at step 704, the
system asks the prober for the touchdown count for the probe card.
Once the test head is secured at step 706, the operator moves the
articulated arm assembly into position to receive the stiffener and
the probe card from the theta ring (step 708). Once the stiffener
is loaded on the hand and the touch memory is in contact with the
memory read station, operational data, including the number of
touchdowns, may be written to the touch memory at step 710. The
system then checks to see if the CRC is OK. If not, an error
message to that effect is displayed, and system operation is
suspended (steps 712-716). If the CRC is OK, the system notifies
the operator that the particular probe card has been unloaded at
step 718. The loaded flag and the unload request flag are then
cleared at step 720.
In FIGS. 14-18, a process for operating the Autoloader 3A is
depicted in a series of logical flowcharts. At step 800, a power up
sequence is initiated after which a system test is run at step 808.
If any errors are detected in the system test, an error message is
displayed and system operation is suspended. If no errors are
detected, the system checks to see whether a stiffener is currently
present in the prober (step 814). If a stiffener is present, a
loaded flag indicating the presence of the stiffener is set. If no
stiffener is present, the loaded flag is cleared (step 818). The
system then checks for a load magazine button at step 820. If the
load magazine button had been pushed, the system runs a load
magazine routine in which the operator may place new probe cards
into the magazine. If the load magazine button was not pushed, the
system checks for any commands from the GPIB (step 824) and decodes
and executes the GPIB command if one is received (steps 826-834).
The decode GPIB command routine (step 830) is illustrated in FIG.
15, and is responsible for, among other things, loading and
unloading the probe card stiffener (steps 922-926 and 904), reading
and writing touch memory data (steps 916 and 932), and moving the
theta ring to and from the home position (steps 950 and 938).
Referring again to FIG. 14, if a GPIB command is not received, the
system determines whether the operator has requested a manual mode
(the terminal emulator mode described above) in which the operator
may command various functions through the keypad. The decode keypad
command routine (step 852) is illustrated in FIG. 16, and is
responsible for, among other things, loading and unloading the
probe card stiffener (steps 1016-1020 and 1004), displaying touch
memory data (step 1042), and moving the theta ring to and from the
home position (steps 1060 and 1048-1052). A diagnostics routine may
also be run (step 1034-1038) in the decode keypad command
routine.
If neither a GPIB command is received or manual mode is requested,
the system checks whether specific commands to either load probe
card #1 or probe card #2 from the magazine has been received (steps
858 and 862). If the system is not already in tester mode, manual
mode is set and the appropriate probe card is loaded (steps
866-876).
The load and unload probe card routines are illustrated in FIGS. 17
and 18, respectively. To load a probe card, the system first
determines whether the unloaded flag is set at step 1202. If so,
the theta ring is commanded to the home position at step 1206. The
touch memory from the appropriate probe card stiffener is polled in
steps 1208-1212. If the CRC is OK, the touch memory repair flag is
in the correct state, and the maximum number of allowable
touchdowns for the probe card has not been exceeded (steps 1214,
1222 and 1228), the system proceeds with the loading of the probe
card (steps 1234 to 1240).
The unload probe card routine will now be described with reference
to FIG. 18. The system first determines whether the loaded flag is
set at step 1102. If so, the system asks the prober for the number
of touchdowns which occurred over the time period that particular
probe card has been loaded (step 1106). The system then secures the
prober (step 1108) and then unloads the probe card stiffener with
the arm/hand assembly (step 1110). When the stiffener is back in
the magazine, the system updates the data in the touch memory (step
1112) and sets the unloaded flag (step 1114).
The above descriptions are illustrative and not restrictive. Many
variations of the invention will become apparent to those of skill
in the art upon review of this disclosure. Geometries of the
individual elements my vary, and thus are not shape restricted. A
wide variety of circuit elements could be utilized in place of
those described herein. Moreover, it will be apparent that circuit
elements could be replaced with software functionality, or,
conversely, that software functionality could be replaced with
circuit elements.
The scope of the present invention should, therefore, be determined
not with reference to the above description, but instead should be
determined with reference to the appended claims along with their
full scope of equivalents.
* * * * *